We are currently busy updating our SSL certificates across all of our servers as the old wildcard certificates for *.fido.net and *.server.fido.net are due to expire on Friday.
As such you may receive an SSL certificate warning if you were trusting the old certificate on your domain, or if you connect to a hosts alias that uses that certificate but has a different domain name.
This is “normal” behaviour and it should be safe to accept the new certificate which expires in 2018